Rear driveline disconect????

[smokeater87]

Sorry if this is a stupid question but i was looking on FRORF's website and came across this   http://frontrangeoffroadfab.com/nfoscomm/catalog/product_info.php?cPath=28&products_id=97&osCsid=34df32c2422bd91ada2f62eb2cc0b883

I was wondering what the benifit of this would be.Is it like a front dig to just have power to the front tires? Thanks for the clearification guys